Hard Drives for a NAS

What a NAS Asks of Its Drives

A hard drive in a NAS lives a much harder life than one in a laptop. Understanding that life is the key to every choice ahead.

The drive in your computer spins up when you need it and rests when you walk away. A NAS is different. It is designed to stay on around the clock so your files are always ready. That means the drives inside may spin for months without a break.

• Always on. It runs 24 hours a day, 7 days a week, for years.
• Neighbors. It sits next to other drives, all vibrating at once.
• Steady work. It may be read from and written to at any hour, including overnight backups and scans.

Why NAS-Rated Drives Exist

NAS-rated simply means a hard drive that the maker built and tested to run all day, every day, packed in beside other drives.

The makers did not invent these drives to charge you more. They built them to solve real problems that show up when a drive never rests. A few things are genuinely different inside.

• Built for 24/7. The moving parts and the motor are rated for continuous running, not just an eight-hour workday.
• Vibration-tolerant. When several drives spin together they shake each other. NAS drives have sensors and sturdier parts to stay accurate through that shaking.
• Smarter firmware. Firmware is the tiny built-in software on the drive. NAS firmware is tuned to recover from a bad spot quickly instead of freezing while it tries and tries, which can confuse the NAS.
• Longer warranties. Makers back these drives for more years because they expect them to work harder.

NAS-Rated vs Desktop Drives

A plain desktop drive is cheaper, and it is tempting. Here is an honest side-by-side so you can decide with open eyes.

The money you save on desktop drives is real, but small compared to the value of what they hold. A desktop drive can work in a NAS for a time. The problem is that it tends to wear out sooner and stumble under vibration, and in a storage box a stumble can mean lost files.

A Word on Shucked Drives

Shucking means buying an external USB drive on sale and cracking the plastic case open to pull the bare drive out for a NAS. It is a popular way to save money. It also comes with catches.

The drive inside an external case is sometimes a fine drive and sometimes a lower grade one. You often cannot tell which until the case is open, and by then you cannot return it as an external drive.

• Warranty usually voided. Opening the case typically ends the warranty. If the drive fails, you are on your own.
• Unknown grade. The drive inside may not be NAS-rated, and its recording type may be the slow kind covered on the next page.
• A power quirk. Some shucked drives have a pin that must be taped over or they will not power on in a NAS. This varies and can be fiddly.

The Recording Type That Matters

This sounds technical, but it is worth one page because the wrong type can make a NAS painfully slow, especially during a rebuild.

Hard drives write your data in tracks, a bit like grooves on a record. There are two ways the maker lays those tracks down, and the difference matters a great deal in a NAS.

Buy Identical Drives

When a NAS uses several drives together, they work as a team. A team works best when every member is the same.

The plainest advice in this whole guide is this: buy all your drives the same brand, the same model, and the same size. It keeps your system predictable and avoids a pile of small problems.

• Same size, no waste. When drives are pooled together, a bigger drive is often treated as if it were as small as the smallest one. Mix a large drive with small ones and you pay for space you cannot use.
• Same speed. Mismatched drives run at the pace of the slowest, so one slow drive drags the whole box down.
• Simpler support. If something acts up, one matched set is far easier to diagnose than a grab bag of odds and ends.

How Much Space You Really Need

The most common mistake I see is buying too little, filling it, and having to start over. Let's size it properly the first time.

Start by adding up what you already have, then plan for growth. Storage is measured in gigabytes and terabytes. One terabyte, written TB, is about a thousand gigabytes. Most family libraries live in the terabytes.

• Count what you have now on every computer, phone, and old drive.
• Add the things not yet on a computer, like boxes of DVDs or old tapes you plan to convert.
• Double that total to leave room for the next few years of photos, video, and files.
• Then round up to the next drive size. Running out is a headache; a little extra room is a relief.

Usable Space Is Less Than the Number

This surprises almost everyone. The space you can actually use is smaller than the total on the boxes, and that is by design.

A NAS usually sets aside some of your drive space for protection, so that if one drive dies your files survive. This protection is called RAID, which is a way of using several drives together as one. The safety it gives you costs some space. That trade is almost always worth it, but you need to plan for it.

• Mirror (two drives, one copies the other): you can use about half the total. Two 4 TB drives give you roughly 4 TB of usable space.
• Single-drive protection across a set: you lose about one drive's worth. Four 4 TB drives give you roughly 12 TB of usable space.
• Two-drive protection across a set: you lose about two drives' worth, for extra safety on larger systems.

Rough Capacity At a Glance

These are round, real-world numbers to help you picture what different setups give you. They are approximate, not exact.

To picture what that holds: a few terabytes is room for a large family photo and document library. Ten terabytes and up starts to comfortably hold home video and a movie collection. Your mileage varies with how much video you keep.

How Many Bays and Drives

A bay is a slot in the NAS box that holds one drive. The number of bays sets how many drives you can install and how you can protect them.

You do not have to fill every bay on day one, but the number of bays shapes your choices. Here is how to think about common sizes.

Match Drive Count to Your Plan

How many drives you buy should follow how you want your files protected. Decide the protection first, then count the drives.

Protection here means how many drives can fail at once without you losing anything. More protection needs more drives, because some of them are holding the safety net instead of your files.

• Want the simplest safety? Two drives as a mirror. One can fail.
• Want more space with safety? Three or four drives with one-drive protection. Any one drive can fail.
• Want extra safety on a bigger box? Five or six drives with two-drive protection. Any two can fail at once.

New vs Used: Buy New

This is the page I would underline twice. For a NAS, buy new drives. A used drive is a gamble with your files as the stakes.

A hard drive wears as it runs. When you buy used, you have no honest way to know how many hours it already spun, how hot it ran, or how it was handled in shipping. A seller can wipe the numbers that would tell you. You are buying a mystery.

• A NAS pools drives together, so one weak drive puts the whole set at risk.
• Used drives often arrive near the end of their life, right when a NAS will run them the hardest.
• If a used drive fails during a rebuild, you can lose everything the NAS was protecting.
• There is usually no warranty to fall back on.

Warranty: Check Before You Buy

The warranty is the maker's promise to replace a drive that fails within a set number of years. It is a real part of the value.

NAS-rated drives usually carry a longer warranty than desktop drives, because the makers expect them to work harder and trust them to last. A longer warranty is both a safety net and a quiet signal of quality.

• Note the warranty length before you buy, not after
• Buy from a seller who sells the drive as new, so the warranty is valid
• Keep your receipt and the drive's serial number in a safe place
• Look up how the maker handles a claim, so you are not learning it in a crisis

SSD or Spinning Hard Drive?

You will see two kinds of storage for sale. Knowing which fits a NAS saves you money and disappointment.

For the vast majority of homes and small offices, the answer is simple: NAS-rated spinning hard drives for your storage, and maybe an SSD later if your box supports one and you want extra speed.

• For your main storage, use spinning hard drives. They give you the terabytes you need at a price that makes sense.
• An SSD can help as an optional speed booster in some NAS boxes, acting as a fast lane in front of the big drives. This is a nice extra, not a requirement.
• All-SSD storage is wonderful and fast, but for most homes the cost per terabyte is hard to justify for bulk storage.

Noise, Heat, and Power

Because a NAS runs all the time, the little things about a drive, how loud it is, how warm it runs, and how much power it draws, add up over the years.

Spinning drives make a soft hum and an occasional clicking as they work. It is normal. Several drives together are louder than one. If the box will sit in a bedroom or a quiet office, put it in a cabinet or a closet, or lean toward fewer, larger drives to keep the noise down.

Where to Buy and Spotting Fakes

Sadly, counterfeit and relabeled drives do turn up online. A few simple habits keep you clear of them.

• Buy from the maker directly, a major retailer, or a seller with a long, solid track record.
• On marketplaces, prefer items sold and shipped by the marketplace itself or by the brand, not by an unknown third party.
• Be wary of a price that is far below everyone else. That is the most common bait for a fake or a used drive sold as new.

Plan for a Drive to Fail

Every hard drive fails eventually. That is not gloom, it is just how they work. A little planning turns a failure into a shrug.

Because your NAS protects your files across several drives, one drive failing does not mean losing anything, as long as you replace it promptly. The goal is to make that replacement quick and calm.

• Know your model. Keep a note of the exact drive you bought so you can order the same one fast.
• Consider a cold spare. Buying one extra matching drive to keep in a drawer means zero waiting when one fails.
• Turn on health alerts. Let the NAS email you at the first sign of a drive going bad, so you act early, not late.
• Replace promptly. While a drive is missing, your safety net is down. The sooner you swap it, the safer you are.

Putting Your Drive Plan Together

Let's turn everything into one short plan you can act on. Work down this list and you will buy the right drives with confidence.

That is the whole job. Take it one line at a time and there is nothing here you cannot handle. And if you would rather I sat beside you while we picked and installed them, that is exactly the kind of visit I love.

• Add up your files today, then double it for the future
• Round up to a drive size that gives you room to grow
• Choose how many drives to lose safely: one-drive or two-drive protection
• Count the drives that plan needs, and pick a box with enough bays
• Buy NAS-rated, CMR drives, all the same model and size
• Buy new, from a seller you trust, and check the warranty

What's in the 27-page PDF

• Why some drives are built for a NAS and others are not
• How to figure out how much storage you really need
• Why usable space is always less than the number on the box
• How many drives to buy, and why they should match
• The truth about used drives and shucked drives
• Whether an SSD or a spinning hard drive is right for you

Why I wrote this

I write these as printable handouts because a guide you can keep in a drawer beats a web page you have to find again. No jargon, no judgment, no rushing. If you'd rather have someone sit beside you and go through it together, that's a flat $99 first visit with the 30-day follow-up included — serving Portage County from Atwater, Ohio. — Bill